Hi everyone I'm in some way new with PyQGIS and I've been trying to run a script in QGIS 3.0 without success (it prefectly ran in 2.18) and always get the same error:

AttributeError: module 'processing' has no attribute 'runalg' During handling of the above exception, another exception occurred: Traceback (most recent call last): File "C:\PROGRA~1\QGIS3~1.0\apps\Python36\lib\code.py", line 91, in runcode exec(code, self.locals) File "", line 8, in TypeError: catching classes that do not inherit from BaseException is not allowed

Does this has something to do with PYTHONPATH? I can't even see the list of algorithms when typing: processing.alglist()

2 Answers 2


In QGIS 3, use processing.run.

For instance:

QGIS 2.x processing.runalg('gdalogr:convertformat', ...

QGIS 3.0 processing.run('gdal:convertformat', ...

  • It works perfectly fine. Also how can I see the list and options of algorithms? I've tried processing.alglist() and processing.list() but both throw a similar error. Commented Mar 14, 2018 at 17:28

This is not an answer to the original question, but to a follow-up question in a comment ("Also how can I see the list and options of algorithms?").

In QGIS 3, the processing algorithms can be listed in the QGIS Python console (Python 3) using (see https://gis.stackexchange.com/a/274902/22646 and https://gis.stackexchange.com/a/274874/22646):


To list the names (IDs):

for alg in QgsApplication.processingRegistry().algorithms(): print(alg.id())

Getting help for an algorithm (including input parameters and output):


There is also:


But it does not seem to include algorithms from for instance gdal and grass.

  • The QGIS documentation has now been updated (see docs.qgis.org/testing/en/docs/user_manual/processing/…). Commented Jun 28, 2018 at 23:27
  • Great answer, @Håvard Tveite . I am having trouble running an external PyQGIS script though, since it cannot find the processing algorithm I'm trying to run: processing.run("qgis:rastersampling", params) I can run any ("native") processing algorithm easily by adding QgsNativeAlgorithms() via the following line: QgsApplication.processingRegistry().addProvider(QgsNativeAlgorithms()) But I'm not sure how to add a similar line to add any of the "qgis" processing algorithms. Any ideas?
    – grego
    Commented Jul 30, 2020 at 18:28

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